Need some help...have a 88GTA that had stock brake system. This winter I upgraded the rearend to a strange 12 bolt S60 rearend with wilwood brakes. Got everything hooked up and bled the brakes and noticed my brake light (on the dash) would come on when testing the brakes in my garage with car on jackstands. Bled the brakes again and still got the same result. Thought maybe I wasn't pulling enough engine vacuum and would need to go out and drive the car.

Since that time I decide to upgrade the front brakes with new wilwood rotors and brakes. Got everything installed, had a buddy come over to help bleed the brakes, this time I did all four brakes again. With the engine off, I can pump the brakes up and the pedal will get firm. As soon as I start the car the brake pedal will go straight down the floor. I purchased everything from Strange, which they have a call into Wilwood about this issue, because I'm sure I'm not the first person that has come across this issue before.

I'm thinking that going from the stock OEM brakes that had a total of 4 pistons (1 piston - per caliper) to my new set up with the wilwood brakes (4 pistons - per caliper) that the master cylinder doesn't have the capacity (volume) to make my new wilwood brakes work the way that they should.

At the end of the day I really don't want to convert everything over to manual brake set up if I dont have to.

Also couple of other things to note:
* I do have a vacuum reservoir that is hooked up and worked great before I made all of the brake changes.
* I can build up 18-20 inches of vacuum and still start the car and have pedal go to the floor. (I do have a vaccum gauge in the car)
*Brake booster still holds vaccum, once I pull the check valve off the booster a you can hear air going back into the booster.

Any help would be great. Thanks.

 

Hey any update on this? It kind of sounds like a similar problem I have been having.

-Thomas

 

I ended up buying a new master cylinder and converted everything to manual brakes.